1. Field of the Invention
The present invention relates to a magnetic head-positioning system, a magnetic head test system and a magnetic disk test system. The present invention specifically relates to a test system to have a magnetic head aligned with a target track on a magnetic disk, which is fit especially for an application in which an accurate positioning range for the magnetic head to be accurately positioned is relatively large.
2. Description of the Related Art
A magnetic head used for a magnetic head or used to store data on and reproduce the data from a magnetic disk has to be tested on its properties before it is assembled in a magnetic head system, according to Japanese Laid-open Application No. 2006-268955. The magnetic head is tested with a head gimbal assembly (referred to as “HGA” hereinafter) into which a head suspension and a magnetic head are assembled. When the magnetic head is tested, data is stored on and reproduced from a magnetic disk with the magnetic head kept floated over a magnetic disk being rotated by a spindle motor.
A piezoelectric actuator is often used for an actuator to accurately position a magnetic head. Since the piezoelectric actuator used for a fine actuator generally generates a displacement from as small as a few micron meter to 20 micron meter, it is necessary to make use of a displacement magnifying mechanism to mechanically magnify the displacement generated by the fine actuator. The principle of the displacement magnifying mechanism is a lever which is well known. According to Japanese Laid-open Application No. 2004.048955, the displacement generated by a piezoelectric actuator is magnified by a lever. According to Japanese Patent No. 3,612,670, vibration of the displacement magnifying mechanism is reduced by a damping member fitted in the displacement magnifying mechanism with which the displacement generated by a piezoelectric actuator is magnified.
According to Japanese Patent No. 3,539,332, there is another type of a displacement magnifying mechanism for an actuator which has an arm whose root portion is displaced by a couple of actuators to generate displacements and which turns as the actuators generate displacements and generates a magnified displacement at the extremity portion of the arm.
In the test system to test a magnetic head, a HGA is made to follow a target track by a fine actuator being actuated, which is fixed on a coarse actuator. The target track is not always on concentric circles about the rotation center of a magnetic disk and has a first order strain on rotation, that is, eccentricity, and a strain of higher frequency components. The eccentricity of the target track can be created by a deviation of the center of the target track which is already written on the magnetic disk from the rotation center of the spindle. This deviation results from an assemblage error caused when a magnetic disk is assembled with a spindle. The eccentricity of the target track also results from the strain caused by the written target track itself which is not a complete circle. In the case of the magnetic disk of Discrete Track Media (DTM) or Bit Pattern Media (BPM), on which the target track is written in advance, the position deviation of the center of the target track from the rotation center of the spindle is created when the magnetic disk is mounted and the eccentricity due to this deviation tends to be relatively large. If this eccentricity becomes larger, the stroke of the fine actuator to drive the HGA on which a magnetic head is mounted needs to be larger.
Furthermore, there has been a need to make the fine actuator smaller and less costly.
One of the objectives of the present invention is to provide a smaller and less costly head-positioning system which is capable of generating a larger displacement and having a better positioning accuracy.